Few studies have examined the prevalence of DSM-IV Inhalant Use Disorders or the relationship of inhalant intoxication to adverse biopsychosocial outcomes, high-risk behavior, and neuropsychiatric impairments among youth at high risk for the occurrence of inhalant-related problems. Specific aims of the proposed RO3 are to: 1) Describe the prevalence of DSM-IV Inhalant Use Disorders and prior episodes of interpersonal violence, criminal acts, high-risk behaviors and other adverse biopsychosocial outcomes associated with inhalant intoxication in a state population of incarcerated youth, 2) Describe the prevalence of nonprescription asthma inhaler abuse, reasons for abuse, characteristics of incarcerated youth who abuse inhalers, and adverse consequences of inhaler intoxication, and 3) Describe the nature and severity of cognitive and psychiatric impairments among heavy adolescent inhalant abusers relative to matched non-users and the persistence of these impairments over six months. All youth (N equals approximately 716) incarcerated in Missouri Division of Youth Services (DYS) institutions will be screened for lifetime inhalant use. Inhalant users will complete assessments of legal, social, psychological, and medical consequences associated with episodes of inhalant intoxication and measures of attitudes toward inhalants, contexts/modes of use, and DSM-IV Inhalant Abuse/Dependence. The proposed research will also yield important new findings describing the prevalence and characteristics of nonprescription asthma inhaler abuse. Further, the proposed RO3 presents a unique opportunity to study the nature and reversibility of specific neuropsychological impairments/psychiatric syndromes in youth at high risk for the development of inhalant related neurotoxicity and associated functional impairments. The project incorporates a case-control study comparing heavy recent adolescent inhalant users to a matched sample of inhalant-negative youth across measures of cognitive performance and psychiatric symptoms. Case-control subjects will complete assessment batteries shortly following their incarceration and 6-months later. Study findings will yield key information about the prevalence of DSM-IV Inhalant Use Disorders among youth in correctional settings and new data regarding adverse legal, social, and health outcomes and persistent neuropsychiatric impairments associated with inhalant intoxication. Study findings will contribute to more effective prevention and treatment efforts with youth at high risk for inhalant-related problems.